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Ultrasport 1000 - debugging help.

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Ultrasport 1000 - debugging help.

Old 08-25-2007, 09:40 PM
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Default Ultrasport 1000 - debugging help.

Hello US1000 drivers,
The purpose of this post is to get my US1000 debugged and to the optimum configuration quicker than the trial and error method that I using. Sure, I'll get there, but it may cost millions of dollars and cost me hundreds of props. Therefore, I'm looking for the 'solution set' for my woes.

The Setup:
US1000, ST2500 w/pipe, and APC 16x8 prop
ST2500 is setup 0-0, no other incident changes to any of the flying surfaces have been made. Exactly per plan.
Fuel: 15% Coolpower
Plug: Fox idle bar
Taildragger configuration.
AUW: 13 lbs 0 oz.
ASL: 6500' at the field, 8100' at my current location.

1. Balance point - the plans state that the ideal CG should be 5 1/4", but a +/- 1/2" variance is allowed - mine is at 5 3/4" - the very aft end of the recommended CG.
2. Lateral balance - dead on.

The Observations:
1. Knife edge transitions fine - I put in the recommended coupling and it tracks knife edges.
2. Roll to inverted flight seems fine too.
3. Seems overproped - but the 16x8 is what ST recommends. Rev's OK for a big Tigre, but doesn't seem have the gitty up that I'm wanting. I'm still experimenting with engine setup (with an ST - you have to sneak up on the right settings) - still running a bit rich at this point.
4. Even though the balance point is at the aft most position, on takeoff the US1000 tail comes on plane very early ... and quickly, resulting in a nose down attitude on TO - really weird. This has lead to me trying different prop diameters with the benefit of actually changing out the props. I know this sounds like an incidence issue - but I've double checked that many times.
5. In contrast and contradiction to issue#4, my US1000 seems to float forever! Downwind deadsticks are no issue - this thing penetrates extremely well and I can still wind up landing at the end of the runway on a downwind approach with no power. Maybe its the way I'm going about landing this thing (which I have not ruled out), but this behavior indicates a slightly nose heavy preference - again in contrast to #1 and #2 above.

The Questions:
1. What prop/fuel combo are you guys using out there for this setup?
2. What CG are you using for this configuration?
3. What explanations are there for what I'm seeing in the flight behavior? I'm a little puzzled right now.

Thanks Folks! I know one of you US1000 gurus has the answer.
Old 08-26-2007, 07:05 PM
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Default RE: Ultrasport 1000 - debugging help.

Before you do anything else, clip the wings to 72". The 1000 was originally designed as a 72" span but Great Planes increased it to 80" by adding the last bay on each wing. (To be IMAA legal, don't you know.)

The long wing slows the roll rate down, reduces yaw precision and tracking and makes it float forever on landing.

The tail up attitude sounds like wheel drag. Too much toe-in? Gear to far back? Wheels not turning smoothly on the axles? Do you have retracts? If so, put a flat washer between the retract and retract mount on each REAR mounting screw to angle the gear slightly forward.

Dump the ST and go with an OS 1.60. Worth 10 times the difference in price.

Jim
Old 08-27-2007, 11:12 PM
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Default RE: Ultrasport 1000 - debugging help.

Jimmy’s right, dump the ST-2500 for the OS! I had a US1000 when the ST-2500 was the only engine commercially available for the plane, unless you wanted a 1.08 that would fly it like a trainer. I had 400 flights on my US1000 with a ST-2500 when I sold it and the guy who bought it cut the two outer bays off and replaced the ST with a Moki 1.5 then it flew like the 60 size.

My St-2500 gave me many opportunities to dead stick it and it will glide for ever. To land it you need to pull the nose up and set the attitude with the E I go for a high nose at first then go to level attitude once the energy carried into the turn is bled off. Then use the T to govern the rate of decent. For a long time I used spoilerons but still would pic up too much speed if I let the nose drop below the horizon.

The ST-2500 is the most cantankerous engine I’ve ever owned. I used to carry two spare carbs. For when I had problems getting it to run correctly, and could change them out fast because it was so common. Taking them home to tear down and clean. I used a 18x8 cut down to a 17x8 because we have noise limits, those that built them and used the ST-2500 always seamed to seek me out to get their planes running so I know that the 16x8 is the prop to use as everyone without sound restrictions used it, and their ST-2500 ran much better than mine once I showed them the trick to getting the back pressure correct. The most common problem with the ST (affectionately dubbed Sucker Tiger at my field) was that after reducing the power Like on the back of a loop, on the next increase of the power the engine would flood unavoidably. We would simply drill 1/8 in dia. Holes in the muffler across from the engines exhaust until the problem was manageable (usually taking two or three). The theory being that there was not enough room in the muffler to allow the exhaust gasses to expand in the small chambers of the muffler increasing the pressure in the tank and not allowing the spent fuel to exit the combustion chamber. In their hay day there was a special fuel mix just for those engines, It's been a while but I think it was 12% oil and 10% nitro, I used it and did not notice a difference.

As for the nose down on takeoff, I needed longer gear anyway so when I bent them I made the axles under the LE of the wing. About an inch forward of the stock ones and that tendency was gone.

Mine was still flying 2 years ago (the last time I saw it) and with a moki it really hums.

Joe

Old 08-27-2007, 11:51 PM
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Default RE: Ultrasport 1000 - debugging help.

Thanks for the posts guys. I was initially dejected by the comments to dump the motor - switching motors is something to consider, but I just got this thing together. That OS1.6 costs a fortune and the Moki isn't much better. Now, I've seen posts where people swear by (not at) the big Tigres, but they readily admit that the big ST's really don't come from the factory 'ready to go'. In fact, things like the spray bar being totally in the wrong position were common carb issues. Therefore, you have to make minute carb adjustments to get it just right - and after that, people reported that it would hold tune and perform very well. Decidedly not an instant gratification, cox-motor, 2 clicks to tune sort of thing.

Since my original post, I've checked on Jimmy's suggestion on the wheels and he was right - there was very unexpected wheel drag, (it sure didn't start out that way), so I fixed that.

Right now, I don't have engine out issues - in fact this motor hand starts on first flip (after warm), and idles/transitions well - I just don't believe that I've got enough top-end, and right now I don't know how to get it there. I started with a very rich setting on the carb and have been sneaking up (read leaning out) on a setting that will be adequate. I don't have any experience with the big Tigres and I know that it won't wind up to 13,000 like a 40 or 60 size motor. So, in part, I really don' t know if I really have everything this motor has to offer. I tached it at FT, using an APC 16x8, at 8900 RPM - and that was at 8100' AGL! I thought that was pretty good - but again, I'm not getting near enough motor for those verticals or even large loops. The motor doesn't sound any different (like it is richening or leaning out, etc).

I'm sure that the OS and Moki's will pull this thing around too, but my gosh - for a motor that is supposed to put out 3.7HP, I would have thought that a measly 13 lb airplane would have been a piece of cake.

So, based on the suggestions that I got so far that don't involve dumping the motor - here's what I got:
1. I'll change fuel to Omega 10% vs the CoolPower 15%
2. Stick with the 16x8 prop.
3. On the gliding forever part - I'll have to learn how to deal with this, The only other plane that I have that acts this way is my LA-1 pattern plane - but even it will slow down. I was simply amazed how much energy the US1000 maintained. I would cut power to low throttle when it passed me and fly it 200' out - make my turn - set up, land and would still roll out to almost the full length of our 700' runway! The first few times I tried to line up on a landing, I did my usual landing pattern - and It was going pretty fast about 10' off the deck when it passed me, and it just wasn't slowing down - swooshhhh!

So, what about my remaining question concerning CG location?
Old 08-28-2007, 10:50 AM
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Default RE: Ultrasport 1000 - debugging help.

8900 is about right for the 2500, without the pipe. You are clearly not getting onto the pipe. When you finally get the pipe tuned right, you should get into the 10,000 plus area. But you will most likely lose the smooth midrange and transition. I had a Perry carb on mine and it ran very well, (most of the time) using a J'tec "snuffler" muffler, and got about 9100 rpm on a good day.

Don't ever go by the manufacturers horsepower numbers. At best they are calculated (not observed) at unrealistic rpm numbers. Sometimes they are pure marketing fiction.

It's been too long and I don't remember where I had the CG, but I'm sure it was at the center of the recommended range or slightly behind that.

If you don't want to clip the wings (I've never understood people's reluctance to do that.) you can use spoilerons to kill some of the lift on landing.

Jim
Old 08-28-2007, 11:36 AM
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Default RE: Ultrasport 1000 - debugging help.

Thanks Jim, I forgot to mention that I do have a pipe on it now, so maybe there's more work to do - Yikes! How, exactly, can you tell whether or not "I'm on the pipe".

On the CG, I remeasured the CG and it is further back than I thought originally (now at 6" vs the 5 3/4 that I thought). So, now on to your other suggestion about clipping the wings.

On Clipping the wings. The aileron strips stop at 4" from the end. If I cut the 4" off - the aileron will be at the end of the wing - is this what you did? Or did you also cut back the aileron strip and fill in the void to duplicate the original profile?

So, it sounds like I can try
1. A perry carb for this thing (anybody know of one for cheap?)
2. Clipping the wing (which you suggested at the outset)
3. Dialing in some spoileron on a mixing switch.

..AJ
Old 08-28-2007, 12:19 PM
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Default RE: Ultrasport 1000 - debugging help.

When the engine comes on the pipe it will pick up 500-1000 rpm at the top end. This is not a smooth transition though. It will pull smoothly until about 3/4 throttle then jump up to full speed. You will need to richen the mixture so that it will not go lean when it goes on the pipe and that will make it blubber in the midrange. Pipes are best for high speed only.

When you clip the wing, you should cut the aileron back and make the configuration the same as it was. The fixed part at the end helps prevent flutter.

1. Buy the Perry Non-pump Mega-carb cut for the ST2500. $54. Also buy a Bisson Sport Muffler for the ST3000. $69 Or you could save yourself a lot of trouble by... you know.

3. If you clip the wings you probably won't need the spoilerons. If you do use them, just set up flaperons with a negetive travel percentage.

Jim
Old 08-28-2007, 09:17 PM
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Default RE: Ultrasport 1000 - debugging help.

also Moki's are excellent engines. i have a burner (.61 on a pipe) and a 2.10 (great sound, power, fuel economy and never once have i had a dead stick)
Old 08-28-2007, 09:38 PM
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Default RE: Ultrasport 1000 - debugging help.

I might have to look into a Moki - not as popular where I am, and the LHS's definitely don't carry them. I do know one guy that has one, and he really likes his. So you all are thinking about a 1.5 Moki? Where is the best place to get them?

..AJ
Old 08-29-2007, 07:38 AM
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Default RE: Ultrasport 1000 - debugging help.

I noticed that everyone telling you to clip the wing lives at very low altitudes. On hot summer days, you will be flying at density altitudes of over 10,000 feet.
Old 08-29-2007, 09:19 AM
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Default RE: Ultrasport 1000 - debugging help.

Moki is now called "Mark" and is sold by Hobby People. They don't make the 1.50 anymore. You now have a choice of a 1.35 or a 1.80. They are great engines, but the same price as the OS 1.60.

Jim
Old 08-29-2007, 09:28 AM
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Default RE: Ultrasport 1000 - debugging help.

Yikes! I would have thought that an Eastern Bloc motor would have been less that an OS (most motors are). Or maybe I just have a tough time spending more than 2 digits for a 2 stroke motor.
Old 08-29-2007, 07:57 PM
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Default RE: Ultrasport 1000 - debugging help.

With engines you pretty much do "get what you pay for".

Jim
Old 08-29-2007, 08:35 PM
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Default RE: Ultrasport 1000 - debugging help.

your us1000 will be a whole different plane with a moki/mark's. My platt Focke Wulf 190 A was an eneamic 64mph top level speed with no vertical on a sicker tiger 2500. with a moki 1.5 its been clocked at 92mph with ample vertical, not as much as i'ld like but at least it gets vertical (more than the sicker tiger 2500 could do). and you wount have to "sneek up" on the throttle settings, just fly it.

Joe
Old 09-16-2007, 11:43 PM
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Default RE: Ultrasport 1000 - debugging help.

Is this a good Pattern plane? Lots of coupling?
Does it need more vert. fin area?
Looks like clipping the wings is a worthwhile mod.

Jim

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